Category:United States Geological Survey

This is the category for the United States Geological Survey (USGS), a federal scientific agency of the US Government that studies landscape, natural resources, and natural hazards.

In most cases it is NOT sufficient, for inclusion in this category, that an article cite USGS for the magnitude of an earthquake. That's routine statistics-gathering for USGS, and probably applies to a large fraction of all articles in Category:Earthquakes, so automatic inclusion of all such articles here would dilute the category, making it less useful for finding articles of particular relevance to USGS.